Polytriazoles find use in many and varied applications. Popular applications include the production of membranes for use in fuel cells. Polytriazoles also find applicability in the area of biocompatible implants.
Furthermore, they can be used as coating materials in a variety of different applications.
Poly(1,2,4-triazoles) are heterocyclic polymers and have been synthesized since the 1940s. Numerous synthesis procedures for polymers are known. Many of these synthesis procedures are for polymers that include 4-phenyl or 4-hydro-1,2,4-triazole-units, such polymers also being characterized by low molecular weights. Aromatic poly(4-aryl-1,2,4-triazoles) with high molecular weights, on the other hand, are primarily synthesized in two ways: According to a first method, ditetrazoles and diazidechlorides are used, leading to polymers with comparably low molecular weights. According to a second method, polymers with high molecular weights are obtained from a cyclocondensation of aniline with high molecular weight aromatic hydrazides in polyphosphoric acid (PPA).
A method according to the latter process mentioned above is described by Holsen J R, Lilyquist M R in J. Polym. Sci.: Part A Vol. 3 (1965) 3905-3917. This method describes a two-step process for the production of aromatic poly(phenylene) 4-phenyle-1,2,4-triazole. Preparation of a prepolymer, an aromatic polyhydrazide, is provided by a polycondensation reaction of terephthaloyl-chloride and isophthaloyl-dihydrazide. The polytriazole first produced is cyclocondensed at temperatures between 175° C. and 260° C. with aniline in PPA. The reaction times vary between 24 hours and 140 hours. At low temperatures, a molecular weight of between 20,000 and 29,000 is realized. The highest inherent viscosities are obtained when the reaction is carried out at 175° C. for 140 hours. A shorter reaction time with higher temperatures results in polymers with lower viscosity.
Virpsha, Travnikova, Krongauz, Korshak describe the synthesis of polytriazoles in a one-step process, cf. Vysokomol. Soyed., 1969, A11/1, 69-72. This process starts with the direct production of poly-1,3,4-oxadiazoles by a reaction of a dicarboxylic acid with hydrazine sulfate. The polyoxodiazole obtained intermediately is not isolated from the reaction mixture, and aniline and PPA are added to the mixture. The mixture is heated with constant stirring. The production of polyoxodiazole occurs at temperatures between 140° C. and 180° C. in a reaction time frame between 0.5 hours and 5 hours. The polytriazoles are produced at temperatures between 215° C. and 220° C. and in a reaction time frame between 12 hours and 35 hours. The resulting polymer is insoluble in organic solvents and has a reduced viscosity between 0.42 dL/g (deciliter per gram) to 5.1 dL/g measured in sulfuric acid, wherein the values get smaller as reaction times increase. Furthermore, it is reported that residual hydrazide groups are observed.
In view of the foregoing, there is an interest in producing polytriazoles that are soluble in organic solvents and contain no residual hydrazide groups. Furthermore, with regard to the production of polytriazoles, lower reaction times, lower reaction temperatures, and resulting high molecular weights are desirable.
To date, polytriazoles have typically been produced in a one-pot process. These polytriazoles contain residual hydrazide groups and are insoluble in organic solvents. The residual hydrazide groups are a disadvantage, as they are neither thermically stable nor chemically stable. Furthermore, long reaction times, e.g., at least twelve hours, and high temperatures are necessary to produce the polytriazoles.
Polytriazoles that are soluble in organic solvents were produced in two-step synthesis procedures that require more time and high temperatures. Two polymers are synthesized in these procedures, and the resulting molecular weights are lower. Furthermore, technical difficulties arise during commercial production of polytriazoles in a two-step process.
DE 691 31 529 T2 describes a light-sensitive resin composition that is suitable for the formation of a heat resistant resin sample for use in semiconductors. The resin composition may comprise, for example, polytriazoles and is soluble in organic solvents such as N-methyl-2-pyrrolidone.
U.S. Pat. No. 4,933,083 describes a composite membrane for the separation of liquids, for example, for use in fuel cells. The composite membrane comprises polytriazoles (among other materials) and is obtained from a polymer solution with N-methyl-2-pyrrolidone.
U.S. Pat. No. 6,096,898 discloses the production of 1,2,4-triazolene in a one-pot method.
Based on the foregoing, it is an object of the present invention to produce functionalized polytriazoles in a method of short duration and with low temperatures, such polytriazoles being easily soluble in organic solvents and having high molecular weights.